Identical red flags of the 3/25th Marines Regiment hang outside the homes of two families in Ohio. Their sons went off to war last March in the same unit. Seven months later, I followed both sets of parents through the emotional homecoming of Lima Company. Only one son was returning alive.

In Paul Shroeder's home, he showed me a photograph of 11 marines, all Lima Company members. Ten of them are now dead, including his son, Augie. They died last August as the marines swept through the town of Haditha.

Two days earlier, six of their colleagues had been shot dead in an ambush, so a convoy had rumbled back into town to hunt down the killers. At least one vehicle drove safely over a hidden bomb. Then a massive explosion blew apart 14 marines.

'His body came back in a casket, had to be closed, could not see him,' Paul says. Then he describes how Augie grew up in New Jersey and Ohio. 'He had two homes and the nature of his injuries are such that he will be buried in two places.' His voice cracks. 'And when Lima Company came home, we received a third part of him in an urn. We don't know where to put that yet.'

That is the hideous reality of war, but until recently President George Bush has done the best job he can hiding it from the American public. More than 2,000 troops have been killed since the invasion of Iraq two-and-a-half years ago, but the President hasn't been to a single funeral.

During last year's presidential election, Bush was a regular visitor to Ohio. It was a key state and in the end victory there handed him his second term.

'He came here when he needed votes,' Peggy Logue tells us as the family prepares to go to Lima Company's homecoming to be reunited with their son, Mike. 'When the marines were killed, there was no sign of him and if he should come now I'd be sickened. Does he think we give up our young so cheaply? He wasn't here for the death and the pain, why should he be here for the glory?'

Not that there was ever much chance of Bush appearing at the homecoming. He doesn't do those either. Nor does this Commander-in-Chief, unlike many of his predecessors, greet the flag-draped coffins of fallen soldiers that traditionally arrive back at Dover air force base. In fact, for the war dead from Iraq he tried to impose a total news blackout, banning the release of pictures taken by the military's own photographers.

It took a lawsuit by an angry professor of journalism to force the release of the pictures. 'I think they've pulled off a really big lie by pretending to be supportive of the military,' Professor Ralph Begleiter says, as he shows me the photos. A CNN reporter for 20 years, he knows what war looks like. 'They've been able to get away with not supporting the military in the most important way, showing respect for those who've made the ultimate sacrifice.'

The photographs of line upon line of coffins are solemn, dignified and very moving, but images of the war dead are not what Bush wants Americans to see, neither does he want them linked to him in any way. Instead, the backdrops are carefully chosen to promote his image as a successful Commander-in-Chief. There he is on the deck of an aircraft carrier, or with the troops on Thanksgiving Day in Iraq or just last weekend at a military base in Pennsylvania at a Veterans' Day rally.

While Bush was surrounded by flag-waving soldiers, we were filming on a massive US Air Force C17 transporter bringing the latest wounded back from Iraq. More alternative images that the American public hardly ever see.

A Channel 4 investigation to be broadcast tomorrow shows the reality of war. We met and travelled with the families and the loved ones of not only those who had been killed but the injured as well. The majority of injuries are caused by the blast of roadside bombs. The defining injuries from this war are brain damage and blown-off limbs. These patients are carried on the plane cocooned in technology to keep them alive: a respirator, chest drains, heart monitor, intravenous lines and a specialist critical care team.

The less seriously wounded have ragged shrapnel wounds in arms and legs or faces pitted with scabs and bruises. During one flight a nurse unwrapped sticky dressings from a man's head to clean the raw burns underneath. The flash flame from a suicide bomber seared his face and the blast had left him almost deaf.

We took off with 17 casualties, but the Pentagon only officially counts nine of them. This is one more way they play down the human cost. Only those injured in battle are included in statistics. The air force man who collapsed with severe pneumonia in Afghanistan, the National Guardsman with blackened fingers and deep burns from faulty electrical kit in Iraq - they don't count, officially. Soldiers have been crushed and paralysed by falling equipment, suffered long-term injuries in overturned vehicles, but they're not in the figures.

The American public has been told that about 16,000 troops have been wounded in Iraq, but if the Pentagon counted everyone flown out for medical treatment - which is how the British Ministry of Defence calculates figures - then the number of American injured would double to more than 30,000.

Most of the casualties we met share Bush's view: we must finish the mission whatever the cost. At a veterans' hospital in Minneapolis, Melissa Stockwell makes an extraordinary sight as she walks towards us wearing shorts. She has one normal leg and one metal pole with a trainer on the end. Her convoy was driving through an underpass in Baghdad when a bomb went off.

'You wonder what life's going to be like. Can I wear heels again? Can I run again?' She was the first female soldier to lose a limb. There have been at least half a dozen others since. 'Freedom isn't free,' Melissa says. 'If that's the price I have to pay for freedom, I'll give my other leg.'

Until recently the scale of the dead and wounded has not hit home. Only where there has been a cluster of local deaths have people in that area realised the true cost of war. That's certainly what's happened in Columbus, Ohio, where Lima Company is based.

Thousands turned out for the homecoming. On a miserable October morning they stood for hours in the drizzle to wait for buses carrying the 150 marines. During seven months in Iraq, almost half their number had been killed or injured, their highest losses since the Second World War. Many of those lining the streets were Vietnam veterans, who know what it is like to fight an unpopular war.

'We were spat at when we came home, they called us baby killers,' one man told us. He was determined it wouldn't happen to this generation. 'We're here to show we support them, that we care.'

An avenue of flags lined the last stretch to the marines' base. Two fire trucks extended their ladders to make an arch and unfurled another enormous Stars and Stripes from the top to hang over the road. I saw several Stars and Stripes tracksuits and dozens of hats and T-shirts. Everyone seemed to be waving a flag or wearing one.

That has been the US government's masterstroke. The President has wrapped up the invasion of Iraq in a patriotic package. To criticise the war is to criticise 'our heroes in uniform', undermining their morale, belittling their bravery.

Even if you strip away the layers of deliberately muddled government rhetoric which tried to link Saddam Hussein to 11 September 2001, many Americans still believe their armed forces in Iraq are defending the US, protecting their own freedoms.

Nowhere is that more obvious than the weekly Friday-night demonstration outside Walter Reed military hospital in Washington DC. Most of the injured troops we filmed will end up there.

On one side of the road stands the anti-war lobby who want the troops home. They are careful to put their case in patriotic terms. 'They're sneaking the wounded in, in the middle of the night', one tells us. 'They don't want people to remember these were real men and women who'd served their country.'

The Bush supporters on the other side of the road jab their fingers towards the opposing group. 'These are a bunch of communists and Marxists. They hate everything about our country, they hate our soldiers,' says one. When I suggest there is no proven link between Saddam Hussein and Osama bin Laden, another spits 'Moron' at me and stomps away. On this side of the road they are far angrier. That's probably because they are losing the argument.

One of the key factors is that those within the military community itself are now coming out and complaining they have been manipulated by the Bush administration. It started with the families, especially the bereaved ones.

'If you have skin in this game and they have died, parents and spouses are very slow or unwilling to admit the death was for anything other than a noble cause,' one Ohio father says. 'I knew this was not a noble cause, and my son's life was wasted and his death and all these other deaths should not have been.' He stops and emphasises each word: 'For no good cause.'

A growing number of soldiers-turned-politicians agree. In Ohio Democrat Paul Hackett stood in a congressional by-election last summer. He lost, but cut a huge Republican majority down to a sliver. One reason was that he had just spent seven months as a marines reservist in Iraq. The voters liked that. When he said, 'The war is over, bring them home, it's a misuse of the military,' no one could call him unpatriotic. Opinion polls now say that 60 per cent of Americans believe the bloodshed is not worth it.

And last Thursday came the most heavyweight backing so far. Senior Democratic Congressman John Murta said: 'The presence of US troops is uniting the enemy against us. It's time for a change in direction.' He thinks all US troops could be redeployed in six months. He's a retired marines colonel with a Bronze Star and two Purple Hearts from Vietnam, not someone you'd call an American-hating commie.

At the Logue house in Ohio, where they are busy painting banners and cooking for the huge party to welcome Mike home, there's still anger and grief at Lima Company's losses. 'I'm a Marine mum,' Peggy tells us.

She's the talker of the family. For much of the interview, her husband, Jerry, sits quietly, choked with tears but nodding at her every answer. 'Mothers know when it's time to stop. It's time to stop. It's time to bring them home.'

· Deborah Davies is the reporter on 'Dispatches: America's Secret Shame' is to go out at 11pm on Tuesday as part of Channel 4's season, The Real War on Terror